1. Field of the Invention
The present invention relates generally to systems for thermal mitigation for tire pressure measurement electronics, and more particularly to tire pressure measurement systems (hereafter “TPMS”) configured to be mounted on a wheel of a vehicle, that uses relatively low cost electronics.
2. Description of the Related Art
Aircraft brake and wheel temperatures are continually increasing. There are many intermittent, peak temperatures seen by the wheel mounted TPMS electronics housing, and it associated internal electrical components.
Large aircraft generate a great deal of heat in their wheels during landing, taxing and taking off. This is due to conduction of heat from the brakes. Because the rubber tire is a poor thermal conductor the heat may build up in the wheel more rapidly than it can be dissipated, especially on aircraft executing repeated take offs and landings, abnormally long taxi distances or aborted take-offs. If the pilot is unaware of the resultant ever increasing temperature it may cause a hazardous tire burst. To prevent this, it is often necessary to apply an obligatory safe cooling period between flights and this can become a limiting factor in the turnaround time of the aircraft.
The actual tire temperature depends on many factors such as, number of previous flights, atmospheric temperature, aircraft weight, taxi distance and use of brakes. A safe obligatory cooling period cannot generally take all of these factors into account and is often unnecessarily long.
Pressure testing devices for the tires of aircraft are well known. One form comprises a mechanical gauge similar to that first invented over one hundred years ago. More modern devices use an electromechanical sensor.
However, with such devices it is only feasible to test the pressure of the tires when they are at a known reference temperature, and this typically means that the tire must be at or close to the ambient temperature, otherwise the hot gas within the tire will be at a greater pressure than the corresponding gas when cold, and the temperature-induced variation will render the pressure reading unreliable.
In the United States, for example, the Federal Aviation Authority (F.A.A.) has expressed the wish that tire pressures be tested every day, but the airlines have indicated that this cannot be achieved in practice because aircraft are often in continual operation for up to three weeks at a time, and the aircraft is not on the ground within this period for long enough for the tires to cool sufficiently for reliable testing to take place.
Because of the high temperatures, expensive and exotic high temperature electronics are may be required.